1. Field of the Invention
The present invention relates to the field of PCS communications using a wireless local loop (WLL). In particular, the invention is concerned with a preferred fax/data interface apparatus that enables the use of a conventional analog fax machine on a wireless local loop (WLL).
2. Description of the Prior Art
In areas where cellular telephone service is available, it is often desirable to configure such service in a building such as a house or office to emulate plain old telephone service (POTS). This is accomplished by configuring a wireless local loop (WLL) using a WLL terminal having an analog telephone port to which a conventional telephone line is connected with analog telephones connected to the telephone line.
The WLL terminal provides wireless communication with the cellular network and provides analog emulation on the telephone lines. That is, the WLL terminal provides dial tone when a connected analog telephone goes off hook, and processes DTMF tones and rotary dial signals from the telephone in order to initiate the corresponding call over the cellular network. For incoming calls, the WLL terminal receives the incoming wireless signals and rings the connected telephones. Also, the WLL terminal includes a data port to which the computer can be connected for handling digital fax signals.
These prior art wireless local loops, however, cannot handle conventional analog telefacsimile (fax) machines. This is because conventional WLL terminals provide the analog interface only in the voice band and analog fax machines operate outside the voice band. This prevents the use of a conventional and inexpensive analog fax machine. As a result, prior art wireless local loops do not provide a complete emulation of plain old telephone service.
The present invention solves the prior art problems discussed above and provides a distinct advance in the state of the art. In particular, the fax/data interface hereof enables the use of a conventional analog fax machine on a wireless local loop.
The preferred fax/data interface apparatus of the present invention includes a digital fax port, an analog fax port, and a signal processor connected between the fax ports for use in the preferred WLL and preferred method of the present invention. The signal processor is operable to receive digital fax signals from a WLL terminal at the digital fax port and to respond thereto by producing analog fax signals representative thereof at the analog fax port for delivery to an analog fax machine by way of a telephone line connected to the analog telephone port of the WLL terminal. Similarly, the signal processor is operable to receive analog fax signals at the analog fax port and to respond by producing digital fax signals representative thereof at the digital fax port for delivery to the data port of the WLL terminal.
In preferred forms, the signal processor is operable to detect CED xe2x80x9creceive fax tonesxe2x80x9d and CNG xe2x80x9csend fax tonesxe2x80x9d at the analog port and to respond by sending a data channel request message by way of the digital fax port to the data port of the WLL terminal. Other preferred aspects of the present invention are disclosed herein.